Japanese Government Railways 4-6-4 Locomotives in Japan

Class Details by Steve Llanso of Sweat House Media

Class C61 (Locobase 3836)

Data from Hiroshi Takagi, both from his website ([]) and personal communication August 2000. His indispensable assistance is gratefully acknowledged. See also A Profile of Japanese Steam Locomotives website put up in 2007 by "Toki S." at [], last accessed 27 September 2015.

These "Hudsons" were converted from earlier D51 Mikados to make up for a deficit in passenger motive power after the end of World War II. Toki S says that 80% of the "reconstruction" was new with only the D51 boiler and other parts being preserved. Piston valve diameter remained 250 mm. The original plan to build 40 C61s and 40 C62s (Locobase 2602) changed and C61 conversions ended at the 33rd engine.

Information from Ejii Nozawa's web site ([]) notes that these were rebuilt from 1947-1949 by Hitachi and Mitsubishi.

Because the measurements above represent the fire side of tubes and flues, a direct comparison with tube & flue heating surface areas of North American and British locomotives requires adding approximately 6-10% to the figures shown.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID3836
RailroadJapanese Government Railways (JGR)
Number in Class33
Road Numbers
Number Built33
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)12.47 / 3.80
Engine Wheelbase (ft / m)34.51 / 10.52
Ratio of driving wheelbase to overall engine wheelbase 0.36
Overall Wheelbase (engine & tender) (ft / m)57.09 / 17.40
Axle Loading (Maximum Weight per Axle) (lbs / kg)30,203 / 13,700
Weight on Drivers (lbs / kg)90,610 / 41,100
Engine Weight (lbs / kg)175,179 / 79,460
Tender Loaded Weight (lbs / kg)106,351 / 48,240
Total Engine and Tender Weight (lbs / kg)281,530 / 127,700
Tender Water Capacity (gals / ML)
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)11 / 10
Minimum weight of rail (calculated) (lb/yd / kg/m)50 / 25
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)68.90 / 1750
Boiler Pressure (psi / kPa)213.20 / 14.70
High Pressure Cylinders (dia x stroke) (in / mm)19.69" x 25.98" / 500x660
Tractive Effort (lbs / kg)26,492 / 12016.58
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.42
Heating Ability
Tubes (number - dia) (in / mm)90 - 2.008" / 51
Flues (number - dia) (in / mm)28 - 5.157" / 131
Flue/Tube length (ft / m)18.01 / 5.49
Firebox Area (sq ft / m2)155 / 14.40
Grate Area (sq ft / m2)35.20 / 3.27
Evaporative Heating Surface (sq ft / m2)1691 / 157.10
Superheating Surface (sq ft / m2)693 / 64.40
Combined Heating Surface (sq ft / m2)2384 / 221.50
Evaporative Heating Surface/Cylinder Volume184.69
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation7505
Same as above plus superheater percentage9681
Same as above but substitute firebox area for grate area42,629
Power L123,271
Power MT1698.61

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